It seems that I'm stuck again cause I cannot pick objects instances correctly.
Look at my events:
In my stage I have:
-two instances of a Crawler object;
-two instances of a Sensor1 object;
-two instances of a Sensor2 object;
sensors have a instance variable "Parent" witch is the UID value of the Crawler instance to which are connected;
Each sensor is correctly positioned to it's crawler.
What I want to achieve is:
-for each crawler, get it's sensors, 1 & 2
-for each of these sensors, check if a collision accurs with obstacles of Backgroundblock;
-doing different things according to collision combinations (S1&S2, S1&!S2, !S1&S2, !S1&!S2)